ABSTRACT Raising the minimum age of legal access (MLA) to tobacco products to 21 decreases access and would likely prevent or delay initiation of tobacco use by adolescents and young adults. However, modern tobacco behavior use among young people is increasingly complex and is characterized by decreased cigarette use, increased use of non-cigarette tobacco product use and, poly tobacco use. In addition, tobacco use patterns and tobacco sales to minors vary based on race/ethnicity. While there has been recent and rapid diffusion of Tobacco 21 policies, little data exist on the process, content, or outcomes of Tobacco 21 laws. The existing evidence for increasing the MLA to 21 holds promise to further reduce tobacco use among young people but the extent to which such policies will be effective for all tobacco products as well as all racial/ethnic groups is largely unknown. Using the Multiple Streams Framework and the Reach, Effectiveness, Adoption, Implementation and Maintenance (RE-AIM) Framework as our conceptual frames we operationalize and assess health policy factors that impact Tobacco 21 Adoption, Implementation and Maintenance. This project uses a mixed methods approach to understand the implementation and impact of policies that raise the MLA to 21, seeking to expand the evidence base with a focus on racial/ethnic groups in the context of a diverse tobacco environment. Specifically, we will: (1) carry out a comparative case study of 15 states using document analysis of Tobacco 21 bills, news media content analysis, and key informant interviews to identify factors that may contribute to the adoption or rejection of Tobacco 21 legislation; (2) conduct a repeated cross sectional tobacco product purchase study to examine implementation of a statewide Tobacco 21 law in New Jersey; and, (3) describe the impact of Tobacco 21 laws by modeling tobacco use behavior among 13 to 25 year olds in states with and without Tobacco 21 laws using data from the National Survey on Drug Use and Health. The relevance of the proposed research to public health is its ability to improve existing and future Tobacco 21 policies and reduce tobacco use disparities.